Advances in cutting-edge electrode engineering toward CO2 electrolysis at high current density and selectivity: A mini-review

Electrochemical CO2 conversion has been raised as a promising solution for building a carbon-neutral economy under today's circumstances of increasing energy shortages and air pollution from human activities. Research on electrochemical CO2 reduction reaction (CO2RR) is gradually entering a pilot-scale stage. The use of device-level CO2 electrolysis in the production of value-added chemicals and fuels at a high production rate and selectivity is highly required to make the technology economical and sustainable. With more exploration toward device-level performance optimization, it gradually becomes clear that electrode engineering on structures, surface properties, active site distribution, and density, as well as the electrode-electrolyte interface, is more critical than the intrinsic activity of catalytic sites. Taking this into account, this review focuses on interpreting the design principles in aspects with the aim of enhancing the CO2RR toward a specific product yield and production rate. This mini-review summarizes the advances in this dynamic field in the most recent 5 years, including the fabrication of porous gas diffusion electrodes, and self-supporting electrodes, establishment of tandem or cascade electrode function, as well as tuning of interfacial cation buffering and wettability, and analyze the trends in the future scientific and technological development of device-level CO2 electrolysis. Hopefully, this mini-review could provide some insights into the opportunities in the next-generation electrode design for the industrial carbon cycle.